Extension cord fuse plug for outlet connections



J. SILVER Aug. 25, 1953 EXTENSION CORD FUSE PLUG FOR OUTLET CONNECTIONS m m m Filed Oct. 27, 1951 gg/aw J24 1 202 Patented Aug. 25, 1953 EXTENSION CORD FUSE PLUG FQR OUTLET CONN ECTIONS John Silver, Jersey City, N. J.

Application October 27, 1951, Serial No. 253,494

3 Claims.

This invention relates to electrical devices with particular reference to the electric plug used to direct current from an outlet connection to an electrical device such as a lamp, radio receiver, or the like.

As a fire prevention means, invariably the modern electric circuit is equipped with fuses. These fuses are usually located in some remote place and are connected to the main current supply line. If a short circuit should develop somewhere in the electrical wiring system, then the particular fuse controlling the circuit involved would blow, cutting off current to all the devices in the said circuit. Before normal operation could be again had, one would have to locate the short and then replace the consumed fuse.

A short developing in a circuit supplying current to an electrical device such as a lamp, radio receiver, etc., would blow the fuse in the main supply line without any indication as to the source of trouble. Thus the entire circuit would have to be inspected to locate the trouble source.

It is then quite apparent that the conventional system of fuse installation is inadequate to cope with the above described situation. Accordingly it is the general object of this invention to modify the conventional system of fuse installation so as to eliminate the above cited objections.

More specifically, this invention relates to pro-. viding an extension cord plug with a fuse or the like, which will interrupt the flow of current through the extension cord upon the occurrence of a short in the extension cord portion of the circuit. So as to protect the main supply line fuse, the fuse plug is designed to break the circuit before the main fuse is affected. Since the plug and extension cord current is in parallel with the main circuit, the blowing of the plug fuse will not interfere with the remainder of the circuit.

Accordingly, it is the prime purpose of this invention to provide a combined plug and fuse which will both protect the main fuse and indicate the location of a particular short-circuit.

It is a further object of this invention to combine a fuse, a plug and an extension cord.

Another object of this invention relates to combining in one compact unit a plug for an outlet connection and a fuse.

A still further object of this invention relates to connecting the plug contact fingers and the extension cord terminals to separate relatively movable parts.

A still further object of this invention relates to providing the plug assembly with a fuse carrying member wherein said member seals the open end of the plug casing.

A still further object of this invention relates to forming the fuse carrying member from a transparent insulating material such as plastic, so that the fuse condition can be readily ascer- I tained.

provide the fuse carrying member with current conducting means which allows current to pass from the contact fingers to a fuse.

A still further object of this invention relates to providing the fuse carrying member with guide holes serving the dual functions of guiding the contact fingers and providing a retaining means for means to conduct current to the fuse from the contact members.

A still further object of this invention relates to providing the fuse carrying member with means for conducting current from the fuses to the extension cord wires.

A still further object of this invention relates to providing an outlet plug with means for conducting current from the contact fingers through fuses to the extension cord wires wherein the fuses are retained in the plug in such a manner that they can be easily replaced and removed.

A still further object of this invention contemplates a fuse carrying panel member which can be easily installed on a conventional electric plug.

Other objects and structural details will be apparent from the subjoined description taken in connection with the drawings forming a part of this specification and in which:

Figure 1 is an exploded perspective view of a plug showing the component parts of the present invention.

Figure 2 is a plan View of the inner side of the fuse carrying panel member.

Figure 3 is a cross-sectional view taken through plane 33 of Figure 1.

Figure 4 is a perspective View of the fuse holder member making contact with a plug contact finger.

Referring to Figure 3, the conventional plug casing l is depicted with the contact fingers 2 attached to the plug casing partition wall 3 by the attachment means 4 and 5. The partition wall 3 has a centrally located perforation therethrough for the purposes of admitting the extension cord wires 1.

In the conventional plug, the contact fingers 2 and the wires 1 would be interconnected by some metallic conductor generally attached to the wall 3. However, in the present invention there is incorporated a fuse carrying disc shaped panel member 8 which is removably secured to the plug casing I by the groove 9. The panel member 8 is formed preferably from a transparent insulating material such as plastic or the like.

Secured to the panel member 8 are the fuse holder members H] which comprise (see Figure 4) the U-shaped attachment portion II, the contact faces l2 and the holder portions l3. To attach one of the members II] to the panel member 8, the U-shaped portion H is inserted through the holes [4 and [5 of the panel member 8 as shown in Figure 3. The holder portion l3 will thus extend towards the center of the panel along the inner face thereof. To each side of a line joining the two holder portions ID are located the extension cord terminals it, better seen in Figure 2. Both the terminals l6 and the portions ID are provided with aligned fuse reception grooves l8 and I! respectively, which receive the fuse elements l3. It is apparent that the fuse elements can easily be removed and replaced by simply sliding them into and out of the retaining grooves. Both the terminal elements H5 and the holder members ID are formed of a metallic conductor material which can be easily deformed, thereby permitting the holder members to be easily attached to or removed from the panel member 8. The terminal members I6 are secured to the panel by the screws which are threaded into the threaded bores 2|. Electrical contact between the extension cord wires I and the terminal members I5 is made by pressing the wire leads 22 between the adjacent faces of the screws 26 and the terminals l6.

After the terminals It, the holder members If the wire leads .22 and the fuses l9 have all been properly secured to the panel member 8, the contact fingers 2 are inserted through the properly proportioned holes M in the panel member, sufficiently so as to permit the groove 9 to receive and retain the panel member. Thus assembled, it is apparent that in addition to providing fuse means, the panel member also acts as a seal, protecting the internal structure from wearing contact with external sources.

As a means to diminish wearing contact between the outer face of the fuse panel member 8 and the abutting portions of an outlet socket, a protector disc 23, formed of a thin piece of insulating material, is placed in abutting rela tionship with the outer face of the panel member 8. To accommodate the contact fingers 2, the protector disc 23 is formed with socket holes 24.

By virtue of the next compact design of the fuse carrying panel assembly, to convert a conventional plug into a combined fuse plug of the hereinbefore described character would be a simple matter. For example, one need only remove the member which interconnects the contact fingers and the wire lead, and attach the wire leads to the panel terminals.

When in operation the contact fingers 2 are inserted into the outlet socket connection (not shown) whereby current passes from the contact fingers to the contact faces l2 of the holder member, along the holder members I0 to the fuse elements I9, from which the wire leads pick up the current through the terminals [6. The extension cord I can of course be connected to any sort of electrical device such as a lamp, radio, toaster or the like (not shown). If the said device should be the source of a short circuit, obviously an electrical current of great magnitude will surge through the plug fuse. An ordinary plug having no fuse, would pass this high current into the main circuit resulting in the immediate consummation of the main circuit fuse and interrupting all electrical services associated therewith. Before services could be resumed, one would have to locate the short and then replace the fuse. However, with the plug fuse described hereinbefore in use, the said high current would immediately blow the fuse elements I9 located in the plug itself; thus the abnormally high current would be prevented from passing into the main circuit. The fuse design is such that the plug fuse will blow befor the main fuse. Since the circuit through the shorted device is broken, the said device will cease to function, thereby indicating immediately the trouble source. To repair the fuse member, one need only remove the panel member 8, take out the consumed fuse portions and replace them with new fuses. Due to the retaining groove structures l1 and i8, fuse replacement is a matter of a few moments.

It is apparent that the damage and the repair labor resulting from a short circuit of the above described type is materially reduced by the hereinbefore described device.

It should also be noted that due to the transparency of panel member 8, the condition of the fuse elements can be readily ascertained.

While the preferred embodiment of the invention has been described and shown, it should be understood that various modifications, obviously contemplated herein, may be resorted to within the spirit of the invention and the scope of the appended claims.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

1. In a plug adapted for connection to an outlet socket, contact fingers to make such connection, said plug having a peripheral wall and a hollow recess, a transverse partition wall perforated at its center to provide access for the insertion of wire leads, said fingers attached to the partition and extending outwardly, said peripheral wall being grooved transversely at its inner surface to receive a circular plastic disc, said disc containing one set of perforations to receive said fingers, said disc having a second set of perforations, a contact member having prongs parallel to said fingers and two legs parallel to said disc, one of said prongs being received by a perforation of the first set and the other prong by a perforation of the second set, one of said parallel legs extending along the inner face of the disc and including a fuse retaining groove, the other of said parallel legs extending along the outer disc face, said contact member being formed of a highly flexible metallic material, whereby said contact member can be easily attached to the disc member, including a terminal member removably secured by screw threaded means to the inner disc face, said member including means for making electrical contact with a wire lead, and groove means for removably retaining a fuse, the holder groove and the terminal member groove being in alignment whereby fuses can easily be slid into place, and a second disc formed of a thin insulating material to fit the inner bore of the peripheral wall abutting the external disc face whereby the disc is protected from excessive Wear.

2. A plug as in claim 1 wherein the second set of perforations are located closer to the disc cencar than the first set of perforations and parallel to the first set of perforations.

3. A plug as in claim 2 wherein the second said member of line 19 comprises a metallic plate perforated to receive a screw, aligned perforations in the disc a quadrant distance from the first said perforations.

JOHN SILVER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,664,408 Frakes Apr. 3, 1928 1,797,620 Sampson Mar. 24, 1931 1,926,936 Casingena et al Sept. 12, 1933 1,974,700 Adams Sept. 25, 1934 2,451,774 Richter Oct. 19. 1948 

